Also 9 jamb. [f. JAM v.1] The action of jamming; the fact or condition of being jammed, or tightly packed or squeezed, so as to prevent movement; a crush, a squeeze; a mass of things or persons tightly crowded and packed together so as to prevent individual movement; a block in a confined street, river, or other passage.
1806–7. J. Beresford, Miseries Hum. Life (1826), XV. i. 41–2. To be locked up in the very heart of the most crowded of all the rooms, by that elegant jam of human kind which constitutes the great charm of your torments.
1812. H. & J. Smith, Rej. Addr., Theatre, 19. All is bustle, squeeze, row, jabbering, and jam.
1827. Longf., in Life (1891), I. viii. 123. I have been several times to her evening jams; but, as it was Lent, there was no dancing.
1838. J. T. Hodge, in C. T. Jackson, 2nd Rep. Geol. Pub. Lands, 65. In descending we find it … overgrown for miles with elder bushes, and obstructed by jams of trees.
1848. Thoreau, Maine W. (1894), 3. Here is a close jam, a hard rub, at all seasons.
1858. Carlyle, Fredk. Gt., X. ii. II. 592. There being a jam of carriages, and no getting forward for half the day.
1860. Chamb. Jrnl., XIV. 241/1. Everywhere, there was a jam of people.
1863. Sat. Rev., 305. There are two great centres and nuclei of jam, and crush, and obstruction.
1891. C. Roberts, Adrift Amer., 83. The ‘gorge’ or ‘jamb’ was occasioned by some of these large pieces of ice getting piled in such a manner across the river as to form a sort of barrier or dam which backed the water up to a flood level.
b. The tight squeezing of one or more movable parts of a machine into or against another part so that they cannot move; the blocking or stopping of a machine from this cause.
1890. Times, 6 Dec., 12/4. The cocking tumbler can be slewed round, with a consequent jam, by a contact which a soldier in the hurry of battle would not notice. Ibid., 15/4. No jam would ensue, unless the soldier tried to use his rifle both as a single-loader and as a magazine arm at the same time.
c. attrib. and Comb. (mainly in words of the American lumber-trade), as jam-boom, a boom on a river for jamming or blocking the floating logs sent down the stream for transportation; jam-breaker, one who unfixes or breaks up a jam of floating logs (Funk, 1893); so jam-breaking (ibid.); Jam-nut, an auxiliary nut screwed down upon the main nut to hold it (Webster, 1864); jam-weld (Forging), ‘a weld in which the heated ends or edges of the parts are square butted against each other and welded’ (Knight, Dict. Mech., 1875).
1879. Lumberman’s Gaz., 1 Oct. From the jam-boom to the head of the sorting works is a distance of seven miles.
